Several Google security engineers have countered claims that a French security company found a vulnerability in Chrome that could let attackers hijack Windows PCs running the company's browser.

Instead, those engineers said the bug Vupen exploited to hack Chrome was in Adobe's Flash, which Google has bundled with the browserfor over a year.

Google's official position, however, has not changed since Monday, when Vupen announced it had successfully hacked Chrome by sidestepping not only the browser's built-in "sandbox" but also by evading Windows 7's integrated anti-exploit technologies.

"The investigation is ongoing because Vupen is not sharing any details with us," a Google spokesman said today via email.

But others who work for Google were certain that at least one of the flaws Vupen exploited was in Flash's code, not Chrome's.

"As usual, security journalists don't bother to fact check," said Tavis Ormandy, a Google security engineer, in a tweet earlier today. "Vupen misunderstood how sandboxing worked in Chrome, and only had a Flash bug."

"It's a legit pwn, but if it requires Flash, it's not a Chrome pwn," tweeted Chris Evans, a Google security engineer and Chrome team lead, using the security-speak term for compromising an application or computer.

Justin Schuh, whose LinkedIn account also identifies him as a Google security engineer, chimed in with, "No one is saying it's not a legit exploit. The point is that it's not the exploit [Vupen] claimed."

When asked to confirm the source of the vulnerabilities it exploited, Vupen was blunt in its refusal to share any information.

"We will not help Google in finding the vulnerabilities," said Chaouki Bekrar, Vupen's CEO and head of research, in an email reply to questions. "Nobody knows how we bypassed Google Chrome's sandbox except us and our customers, and any claim is a pure speculation."

Last year, Vupen changed its vulnerability disclosure policies when it announced it would no longer report bugs to vendors -- as do many researchers -- but instead would reveal its work only to paying customers.